i use lava rock for the bottom of my pots, and builders sand as about %20 of my mix
the rest being mostly potting mix (peat+perlite) and about 10-15% compost.
i actually like the sand. it provides good drainage and the roots can branch out to a fine mesh.
i remember pulling out a 7-gallon container i had a papaya in, and it seemed to LOVE the sand.
there was a ton of fine roots that grew a very healthy papaya plant for several years.
i had grown it in pure sand just to start the seeds, i removed all but one, and just let it grow.